Surge-detecting relay



June 2, 1925.

Filed May 24, 1923 INVENTOR Ha ry P, Spar/(w. BY

Patented June 2, 1925.

.UNITED STATES PATENT orrlcn.

balance between both elements transformer 4.

nanny r. sraaxnsor PITTSBURGH, PENNSYLVANIA.

' SURGE-DETECTING RELAY.

Application filed May 24, 1923. Serial No. 641,038.

To all whom it may concern:

Be it known that I.. 'Hluzav P. SrAnKns, a

citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful- Improvement in Surge- Detecting Relays, of which the following is a specification. Q i

' My invention relates to" relay systems and particularly to systems for detecting surges in an electrical circuit;

One object of my invention is to provide means for distinguishing between surges of current in an electrical system and gradual increase of current.

Another object of my invention is to provide means for detecting an increase of current when therate of increase thereof exceeds a predetermined rate of change.

A further object of mvinvention is to employ such means as indicated above for controlling an electrical. circuit in which such conditions may occur. I

In practicing my invention, I'provide a balance relay embodying two elements and energize one element from the circuit and control the energization of the other element of the relay by means vof a Kelvin balance device which is also energized from the circuit. As the current in the circuit increases, the'corresponding element of the balance relay is energized and, if such in crease in'tlie circuit current is gradual, the Kelvin balance will control the energization of the counteracting element to effect a If'the in' crease inflthecircu'it current is rapid, such as it caused by occurrence of short-circuit conditions, the corresponding element of the relay will be energized quickly and will serveto operate the relay before the Kelvin balance may correspondingly allect the'ener- 'gi'zation of the counteracting element. The

faulty portion ofthe circuit may thereupon be disconnected;

The single figure of the accompanying drawing is a diagrammatic view "of an elecbodyin my invention,

As i lustra'ted in the drawing, electrical energy is supplied fromasour'ceof supply 1 to a circuit 2 through 'a circuit interrupter 'The'valueofthe current traversing the circuit '2 is measured hy"-ineans of a current trical system containing the apparatus em- Infidel toilisti-nguish between a normal engaged.

the circuit 2, I provide a balance relay 5 and a Kelvin balance 6. i

" The balance relay 5 comprisesan operat ing element 7 that is energized from the current transformer4, a counteracting element 8. a plurality of contact members 9 and '10, engagement of which is controlled by a pivoted member 11, and a springlZ which also serves to control, in cooperation with the elements 7 and 8, the movement of? the pivoted member 11.

The Kelvin balance 6 comprises a stand ard control balance element 15 which is energized from the current transforn'ier i in series with the operating element 7 of the balance relay 5. The pivoted operating element of the balance relay controls, by means of a switching device 16. the circuits of the two field windings 17 and 18 of a reversible motor 19. The motor 1.9 controls a threaded member 20 which, in turn, controls the movement of a sliding contact member 21 in engaging a. resistor '22. The resistor 22 is energized from a source of constant potential 23.

Upon referring to the drawing, it will be seen that the counteracting element 8 is connected to the resistor 22 as to be energizedin accordance with the potential difference across theportion of the resistor includedbetween the point 24 and the point of engagement of the sliding contact memher 21 with the resistor 22. i

As the current in the circuit 2 increases gradually, the operating element 7 of the balance relay 5 1ncreases and tends to effect engagement between the contact members 9 and 10. Simultaneously, however, the switching devicelG of the "Kelvin balance 'efi'ects 'the'energization of the winding of the reversible motor 19 to shift the sliding contact member towards the right-hand side, thereby increasing the potential difference lmpressed upon the counteracting element'8. Thebalance relay 5 is thereby ina'i-ntainedin a stateo'f balance and the contact members 9 and 10 are maintained dis- Upon the occurrence of a surge, such as that caused bys'hort-circuit conditions in the circuit 2, the element 7 becomes immediatelyenergized to a great'de nee, tending thereby to effect engagement 0, the contact members 9 and 10. Simultaneously, as in the other condition, the Kelvin balance operates to shift the sliding contact member 21 towards the right-hand side to increase the energization of the counteracting element 8.

Since the increase in the energization of the counteracting element 8 is dependent upon the rate of speed at which the sliding contact member 21 may be shifted, the 0 )erating element may effect the engagement of the contact members 9 and 10 before the counteracting element 8 becomes suficiently energized to etlect a balance of the relay 5.

Upon engagementof the contact members 9 and 10, the trip coil 25 of the interrupter 3 is energized from the source of energ and the interrupter is opened to disconnect the circuit from the supply source 1.

The relay 5 may be provided with suit able damping means to preclude instantaneous operation, if desired, and to add a min imum definite time element in its operation, in order to i-reclude operation of the relay upon occurrence of ordinary switching surges.

The Kelvin balance may similarly be provided with a time element in its operation in controlling the energization of the counteracting element 8 of the balance relay by providing a gear, or other equivalent reducing element, between the motor and the threaded member 20, to either increase or decrease the speed thereof to control the rate of change of energization of the counteracting element 8.

My invention is not limited to the specific apparatus that is illustrated, since it may be variously modified without departing from the spirit and scope of my invention as set forth in the appended claims.

I claim as my invention:

1. The combination with a distribution circuit of a protective device therefor comprising a balance relay provided with differentially operative elements, means for energizing one element of said relay in accordance with the circuit current, retarded means for energizing another element of said relay to counteract the eiiectiveness of the first element contacts controlled by said elements and switching means in said circuit controlled by the closure of said contacts.

2. A protective control system for an electric circuit comprising a balance relay embodying two elements, means for energizing one element from the circuit, means for energizing the other element from a separate source and a balance device for controlling the energization of the second element to balance the efi'ectof the first element.

3. The combination with an electric circuit deriving its energy from a power system, of means for isolating the circuit when surge-producing conditions occur in the ciragainst overload current of the same magni tude.

, 5. The combination with an alternating current circuit and an interrupter the of means energized from the circuit tor ccn. trolling the actuation of the interrupter upon the occurrence of a surge in the circuit comprising a balance relay embodying an element energized from the circuit.'

(5. In an electric circuit. the combination with a circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs in the system comprising an element energized from the circuit, a counteracting element and means for controlling the effectiveness of the counteracting element in accordance with the circuit current.

7. In an electric circuit, the combination with a circuit interrupter. of means for controlling the actuation of the interrupter when a surge occurs in the system comprising a balance relay embodying an element energized from the circuit and a counteracting element, and a Kelvin balance responsive to circuit currents for controlling the counteracting element.

8. In an electric circuit. the combination with a circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs in the system comprising a balance relay embodying an element energized from the circuit and a counteracting element, including an operating coil, and a Kelvin balance energized from the circuit for controlling the energization of said coil.

9. In an electric circuit, the combination with a circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs in the system comprising a balance relay embodying an element energized from the circuit and a counteracting element, including an operating coil, a variable resistor in circuit therewith and a balance device energized from the circuit for controlling the resistor.

10. In an electric circuit, the combination with a. circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs in the system comprising a balance relay embodying an element energized from the circuit and a counteracting element, and means for varying the IOU within a predetermined rate of change of effectiveness.

11. In an electric circuit, the combination with a circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs in the system comprising a balance relay embodying an element energized from the circuit and a counteracting element, means independent of the circuit for energizing the counteracting element and means responsive to the circuit current for controlling said means.

12. In an electric circuit, the combination with a circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs in the system comprising a balance relay embodying an element energized fromthe circuit and counteracting element, and means responsiveto the circuit current'for controlling the counteracting element independently of the rate of change of circuit current.

13. In an electric circuit, the combination with a circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs, in the system comprising a balance relay embodying an element energized from the circuit and a counteracting element, means for controlling the' energization of the counteracting element within a predetermined rate of change, and means controlled by the balance relay for actuating the interrupter when the rate of change of circuit current exceeds the rate of change of energization controlled by said controlling means.

1.4. In an electric circuit, the combination with a circuit interrupter, of means for controlling the actuation of the interrupter when a surge occurs in the system comprising a balance relay embodying an element energized from the circuit and a counteracting element, means for controlling the energization of the counteracting element within a predetermined rate of change, and means responsive to the diflerential torque of the relay elements for controlling the 1nterrupter.

15. The combination with an electric circuit and an interrupter therein, of means for controlling the actuation of the interrupter comprising two counteracting elements, means for energizing one in accordance with the circuit current, means for controlling the energization of the other element Within a predetermined rate of change of energization in response to current changes in the circuit, and a control element responsive to the differential action of the counteracting elements.

16. In an electric circuit, the combination with a circuit interrupter,'of means for controlling the actuation of the interrupter when a surge occurs in the system, comprising a balance relay embodying an element energized from the circuit, a counteracting element, and retarded means for controlling the effectiveness of the counteracting element.

17 In combination, a distribution circuit, a circuit-interrupter therein, a relay for controlling said circuit-interrupter and means for actuating the contacts of said relay upon the surge of current in said circuit, said means being ineffective upon a gradual in crease of current to the same value.

In testimony whereof, I have hereunto subscribed my name this 14th day of May 1923.

HARRY P. SPARKES. 

